Locomotive control system



March 20, 1951 J. J. STAMM 2,546,023

LOCOMOTIVE CONTROL SYSTEM Filed March 1, 1949 Fig.l.

Air

Compressor v Fig.2. 43

Horsepower wmuzssss; I INVENTOR V Joh J. St omm. @g a ATTO a" EY Patented Mar. 20, 1951 LOCOMOTIVE CONTROL SYSTEM John J. Stamm, Media, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 1, 1949, Serial No. 79,078

6 Claims. 1

My invention relates, generally, to locomotive control systems and, mor particularly, to systerms for controlling the operation of locomotives of the self-propelled type, such as Diesel-electric and gas-turbine-electric locomolives.

A Diesel-electric or a gas-turbine electric locomotive may be accelerated from standstill by increasing the voltage applied to the traction motors, either by controlling the excitation of the field winding of the main generator by means of a master controller, or by means of a mechanically, hydraulically or pneumatically operated throttle mechanism which also controls the eX- citation of the field winding of the main generator, or the field winding of the exciter which supplies the excitation current for the field wind ing of the main generator. In either case there is a possibility of stalling the prime mover if the load on the generator is increased faster than the speed of the prime mover.

An object of my invention is to provide for automatically increasing the excitation of the main generator on a self-propelled locomotive in accordance with the speed of the prime mover.

Another object of Illy invention is to prevent overloading or stalling the prime mover while accelerating the locomotive.

A further object of my invention is to provide a combined accelerating and load regulating ystem for a. self-propelled locomotive.

A more general object of my invention is to provide a control system for a self-prope led locomotive which shall be simple and efficient in operation and which may be economically manufactured and installed.

Other obiects of my invention will be explained fully hereinafter or will be apparent to those skilled in the art.

' In accordance with one embodiment of my invention, the air pressure of the compressor for a gas turbine or the supercharger for a Diesel engine is utilized to control the field excitation of the generator or exciter on a gas-turbine-electric or a Diesel-electric locomotive, thereby eliminating the need for field control by the master controller or throttle. The air pressure of the compressor or supercharger is a function of the speed of the turbine or engine, and the tem erature and the densit of the intake air. Therefore, it is only necessary to increase the speed of the turbine or Diesel engine and the load will be applied automatically in response to the compressor or supercharger pressure. Since this pressure is a direct measure of the ability of the prime mover to develop power, it is-possible, by

proper proportioning of the control means, to match the output of the generator with that of the prime mover. This will prevent overloading or stalling of the gas turbine or Diesel engine.

For a better understanding of the nature and objects of my invention, referenc may be had to the following detailed description, taken in conjunction with the accompanying drawing, in which:

Figure l is a diagrammatic View of a locomotive control system embodying the principal features of my invention, and

Fig. 2 is a set of curves illustrating operating characteristics of the system shown in Fig. 1.

Referring to the drawing, and particularly to Fig. 1, the system shown therein comprises a prime mover iii, which may be either a gas turbine or a Diesel engine; an air compressor or supercharger l i, which supplies compressed air 1 to the prime mover ill; a generator 12, which supplies current to a traction motor 13; a main exciter IQ, and a pilot exciter 5. As shown, the compressor l l, the generator 5 2, the main exciter l4 and the pilot exciter 45 are all driven by the prime mover Ill.

The generator !2 is provided with an armature winding is and a field winding H. The motor [3 is provided with an armature winding [8 and a series field winding E9. The field winding i! of the generator i2 is energized from anarmature winding 2! of the main exciter Hi. This exciter is provided with a differential field winding 22 which is connected in series-circuit relation with the traction motor 53 and the armature 5 of the generator 52. The exciter ii is also provided with a shunt field winding 2-3 and a separately excited field winding 24 which is energized from an armature winding 25 of the pilot exciter [5. The pilot exciter i5 is provided with a field winding 25 which is energized from a battery 2?. Manually operable rheoslats 28 and 29 may be provided for adjusting the current in the field windings 23 and 26, respectively.

In order to provide for automaticall increasing the output of the generator l2, thereby ac oelerating the locomotive or vehicle which is propelled by the motor 13 without stalling the prime mover EU, a variable resistance device 3| is provided for controlling the ener ization of the field winding 26 of the pilot exciter it, which, in turn, controls the energization of the field winding 24 of the main exciter i5, thereby controlling the excitation of the generator i2 and the voltage of the generator. 7 As shown the variable resistance device 3| comprises a stack of carbon 3 discs 32 which are connected in the circuit for the field winding 26 and may be compressed by a spring 33 which biases a lever M to compress the discs 32. lhe lever 35 is pivoted at and compresses the discs 32 when actuated in one direction, and releases the pressure on the discs when actuated in the opposite direction. As is well known, the resistance of the carbon pile 32 varies with the pressure applied to the discs.

As shown, the end of the lever 3 is connected by a link 35 and a bell-crank lever iii to a piston rod 38 for a piston 39 of a pressure-responsive device 40. The piston 39 is disposed in a cylinder 'll. The cylinder ll is connected to the. compressor or supercharger l i We pipe Thus the piston 39 is actuated downwardly by the pressure developed by the compressor or supercharger i i and is actuated upwardly by a spring 42 disposed inside of the cylinder M. A slot is provided in the end of the link 3b which is connected to the lever t l, thereby providing a lost motion connection between the fluid pressure actuated piston 38 and the lever As explained hereinbefore, the air pressure of the compressor or supercharger ii is a function of the speed of the prime mover iii, and the temperature and the density of the intake air. Since this pressure is a direct measure of the ability of the prime mover to develop power, it is thus possible, by proportioning of the control means, to match the output of the prime mover with that of the generator, thereby preventing overloading or stalling of the prime mover while accelerating the locomotive or vehicle.

Furthermore, as previously mentioned, the pressure of the compressor or supercharger. is a function of the air temperature and density. Thus, when operating the locomotive at a low air temperature the compressor pressure will be higher, thereby permitting quicker loading of the turbine or Diesel-engine, which are capable of developing more power at low air temperatures. When the locomotive is operating at high altitudes or high air temperatures the supercharger or compressor pressure is low and the loading of the generator is slower.

In order to permit the prime mover to operate at substantially a constant speed after the vehicle is accelerated a load regulator lt is provided to cooperate with the pressure responsive device 40 in controlling the operation of the variable resistance device 3!. The load regulator t l may be of the type disclosed in Patent No. 2,340,994, issued February 8, 1944 to W. H. Smith. As shown, the load regulator comprises a combined governor and control valve li an auxiliary control valve 4-6 and a power piston il' which is connected to the valve ts by pipes 38 and d9. As described in the aforesaid patent, is delivered under pressure from the governor and control valve 45 to the auxiliary control valve 46 which is rotated at a speed corresponding to the speed of the prime mover Hi. The oil is delivered intermittently from the valve 4% to the power piston 42, thereby applying a pressure to the piston 47 which is proportional to the spec of the prim-e mover.

The fluid pressure device it and the load regulator 44 function to control the generator output in the following manner:

When the locomotive is being accelerated and the speed of the prime mover is low, the compressor or supercharger pressure is low and the variable resistance device PM is expanded by the spring 452 operating through the. linkage mechanism, thereby inserting a relatively high resistance in the circuit for the field winding 26 of the pilot exciter l5. This results in a low excitation for the main exciter i i and the generator 12, which causes the generator to develop a low voltage for starting the locomotive.

Increasing the speed of the prime mover by means of the. throttle mechanism (not shown) will increase the pressure developed by the compressor or supercharger El, thereby actuating the piston 39 downwardly and permitting the spring 33. to. compress the carbon pile 32 to decrease the resistance in the circuit for the field winding 26 of the pilot exciter i By the cumulative action of increased pilot and main exciter speeds with the increased excitation, the voltage. developed by the generator increases, thereby raising the voltage applied to the motor is and increasing the speed of the locomotive.

.As illustrated by the curves in Figure 2, the characteristics of the generator, shown by the curve G, may be so controlled, by the proper proportioning of the various parts of the regulating system, that the loading curve of the generator follows closely the loading curve T of the prime mover. It essential that the curve G be below the curve T at all times during the operation of the locomotive to prevent stalling of the prime mover.

As explained hereinbefore, the load regulator it functions to control the load on the generator E2 to permit the prime mover to operate at substantially aconstant speed after the locomotive has been accelerated. It will be seen that the power piston device t? limits the movement of the lever 34 in a direction to compress the carbon pile 32. Furthermore, the slot i3 permits the power piston 51. to actuate the lever 34 in a direction to decrease the pressure on. the discs 32.

Thus, if the prime mover becomes overloaded and its speed decreases, the load regulator 44 functions to increase the resistance in the circuit for the field winding. 26 of the pilot exciter [5, thereby decreasing the generator voltage and the output of the generator. In this manner the speed of the prime mover is permitted to. increase slightly. Likewise, if the speed of. the prime mover increases above its normal speed, the load regulator i l. functions to decrease the resistance in the circuit for the. field winding 26 of the pilot exciter, thereby increasing; the. load on the generator and decreasing the speed of the prime mover.

From the foregoing description it is apparent that I have provided a system for automatically applying the load to the prime mover of a locomotive or vehicle in accordance with the speed of. the prime mover, thereby eliminating the possibility of overloading or stalling the prime, mover while the load is being applied. Furthermore, the present system permits maximum output to be obtained from the primev mover under varying conditions of air temperature and density. The present system also functions to maintainv a con-- stant speed of the prime mover after the load has been applied.

Since numerous changes may be made in the above-described construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a. limiting sense. 1

I claim as my invention:

1. In a control system, in combination, a prime mover, a generator driven by the prime mover and having an armature winding and a field winding, exciting means for energizing said field winding, variable-resistance means for controlling the energization of said field winding, a fluid compressor driven by the prime mover to supply a compressed fluid to the prime mover, pressure-responsive means actuated by the fluid pressure developed by said compressor, regulating means responsive to the speed of the prime mover, and lost-motion means connecting the pressure-responsive means and the regulating means to the variable-resistance means independently of each other, said lost-motion connections being disposed to permit said regulating means and said pressure-responsive means to cooperate in controlling the operation of said variable-resistance means.

2. In a control system, in combination, a prime mover, a generator driven by the prime mover and having an armature winding and a field winding, exciting means for energizing said field winding, a variable-resistance means for controlling the energization of said field winding, a fluid compressor driven by the prime mover to supply a compressed fluid to the prime mover, pressure-responsive means actuated by the fluid pressure developed by said compressor, load-regulating means responsive to the speed of the prime mover, and lost-motion means connecting the pressure-responsive means and the regulating means to the variable-resistance means independently of each other, said lost-motion connections being disposed to permit said load-regulating means and said pressure-responsive means to jointly control the operation of said variable-resistance means to control the excitation of said generator.

3. In a control system, in combination, a prime mover, a generator driven by the prime mover and having an armature winding and a field winding, exciting means for energizing said field winding, variable-resistance means for controlling the energization of said field winding, a fluid compressor driven by the prime mover to supply a compressed fluid to the prime mover, pressure-actuated means responsive to the fluid pressure developed by said compressor for controlling said variable-resistance means to increase the generator excitation, load-regulating means responsive to the speed of the prime mover for controlling said variable-resistance means to decrease the generator excitation, and lost-motion means connecting the pressure-actuated means and the load-regulating means to the variableresistance means independently of each other.

4. In a control system, in combination, a prime mover, a generator driven by the prime mover and having an armature winding and a field winding, exciting means for energizing said field winding, variable-resistance means for controlling the energization of said field winding, a fluid compressor driven by the prime mover to supply a compressed fluid to the prime mover, pressureactuated means responsive to the fluid pressure developed by said compressor for controlling said variable-resistance means to increase the generator excitation, load-regulating means responsive to the speed of the prime mover for controlling said variable-resistance means to decrease the generator excitation, a lost-motion connection between said pressure-actuated means and said variable-resistance means, and an additional lost-motion connection between said 5 load-regulating means and said variable-resistance means.

5. In a control system, in combination, a prime mover, a generator driven by the prime mover and having an armature winding and a field winding, exciting means for energizing said field winding, variable-resistance means for controlling the energization of said field winding, a fluid compressor driven by the prime mover to supply a compressed fluid to the prime mover, pressureactuated means responsive to the fiuid pressure developed by said compressor for controlling said variable-resistance means to increase the generator excitation, load-regulating means responsive to the speed of the prime mover for controlling said variable-resistance means to decrease the generator excitation, a lever arm for actuating said variableresistance means, spring means for biasing said lever arm in one direction, a lost-motion connection between said lever arm and said pressure-actuated means, and an additional lost-motion connection between said lever arm and said load-regulating means.

6. In a control system, in combination, a prime mover, a generator driven by the prime mover and having an armature Winding and a field winding, exciting means for energizing said field winding, variable-resistance means for controlling the energization of said field winding, a fiuid compressor driven by the prime mover to supply 35 a compressed fluid to the prime mover, pressureactuated means responsive to the fluid pressure developed by said compressor for controlling said variable-resistance means to increase the generator excitation, load-regulating means responsive 40 to the speed of the prime mover for controlling said variable-resistance means to decrease the generator excitation, a lever arm for actuating said variable-resistance means, spring means for biasing said lever arm in one direction, a lostmotion connection between said lever arm and said pressure-actuated means, and an additional lost-motion connection between said lever arm and said load-regulating means, said load-regulating means being disposed to oppose said spring means.

JOHN J. STAMM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,280,587 Thury Oct. 1, 1918 1,745,130 Turner Jan. 28, 1930 1,806,705 Post, Jr. May 26, 1931 2,050,068 Schaer Aug. 4, 1936 2,281,987 Oswald May 5, 1942 2,311,285 Stamm Feb. 16, 1943 2,340,994 Smith Feb. 8, 1944 2,393,621 Adams Jan. 29, 1946 2,472,924 Schwendner June 14, 1949 FOREIGN PATENTS Number Country Date 456,119 Great Britain Nov. 3, 1936 714,683 France Sept. 8, 1931 

